1. Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more particularly to a vertically-aligned (VA) LCD wherein the orientation of the liquid crystal molecules inside pixels are set to a plurality of mutually different directions.
2. Description of the Related Art
Liquid crystal display mainly comprises a liquid crystal display unit having two glass substrates oppositely positioned and a liquid crystal layer interposed therebetween. Vertically-aligned (VA) LCD is a mode using a liquid crystal material with negative dielectric constant anisotropy and vertical alignment films. In the absence of an applied electric field, the liquid crystal molecules are aligned in a vertical direction and a black display appears. When a predetermined electric field is applied, the liquid crystal molecules are aligned in a horizontal direction and a white display appears. Compared to the twisted nematic (TN) LCD, the vertically-aligned (VA) LCD provides higher contrast, higher response speed, and excellent viewing angle.
However, the VA LCDs still suffer from the problems of decreased contrast ratio and contrast reversal when viewed in different directions other than perpendicular to the display area. This is due to the birefringence effect of the liquid crystal molecules inside the liquid crystal display unit. When the incident light passing through the LCD unit at other than a normal angle, such light will interact with the liquid crystal molecules in a manner different from the incident light passing through the LCD unit at a normal angle. Thus, the contrast between a light transmissive (white) state and a non-transmissive state (black) at other than the normal angle is drastically decreased, thus making such displays less desirable for use in many applications, such as flat panel television screens and large computer screens.
The present invention therefore seeks to provide a VA LCD that overcomes or at least reduces the aforementioned problems of the prior art.